Recent mobile computing devices have implemented touchscreen displays that are capable of recognizing more than one finger touches. Referred to as “multi-touch” displays, such touchscreens enable new user interfaces that offer more intuitive interactions with computing devices. A well known example of a computing device implementing a multi-touch display is the iPhone® by Apple Computer, Inc. The market success of the iphone® has spawned many competitors and new software applications. Thus, there is a sudden demand for multi-touch displays.
Conventional multi-touch displays employ capacitive sensors which detect the touch of a finger as a change in capacitance in an array of capacitors underlying the display glass. Descriptions of this technology are provided in U.S. Pat. No. 6,323,846 and U.S. Patent Publication No. 2006-0097991, the entire contents of which are hereby incorporated by reference.
A second multi-touch display employs two resistive panels positioned one above the other which are brought into contact by a finger press on the display glass. By measuring the voltage drop or effective resistance through the panels a processor can estimate the location of the finger press.